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Merge "applypatch: Clean up the function comments."

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This commit is contained in:
Tao Bao 2018-06-20 16:26:02 +00:00 committed by Gerrit Code Review
commit 24e1321bc3
2 changed files with 105 additions and 116 deletions
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163
applypatch/applypatch.cpp
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@ -49,8 +49,6 @@ static int GenerateTarget(const FileContents& source_file, const std::unique_ptr
const std::string& target_filename,
const uint8_t target_sha1[SHA_DIGEST_LENGTH], const Value* bonus_data);
// Read a file into memory; store the file contents and associated metadata in *file.
// Return 0 on success.
int LoadFileContents(const char* filename, FileContents* file) {
// A special 'filename' beginning with "EMMC:" means to load the contents of a partition.
if (strncmp(filename, "EMMC:", 5) == 0) {
@ -80,20 +78,16 @@ int LoadFileContents(const char* filename, FileContents* file) {
return 0;
}
// Load the contents of an EMMC partition into the provided
// FileContents. filename should be a string of the form
// "EMMC:<partition_device>:...". The smallest size_n bytes for
// which that prefix of the partition contents has the corresponding
// sha1 hash will be loaded. It is acceptable for a size value to be
// repeated with different sha1s. Will return 0 on success.
// Loads the contents of an EMMC partition into the provided FileContents. filename should be a
// string of the form "EMMC:<partition_device>:...". The smallest size_n bytes for which that prefix
// of the partition contents has the corresponding sha1 hash will be loaded. It is acceptable for a
// size value to be repeated with different sha1s. Returns 0 on success.
//
// This complexity is needed because if an OTA installation is
// interrupted, the partition might contain either the source or the
// target data, which might be of different lengths. We need to know
// the length in order to read from a partition (there is no
// "end-of-file" marker), so the caller must specify the possible
// lengths and the hash of the data, and we'll do the load expecting
// to find one of those hashes.
// This complexity is needed because if an OTA installation is interrupted, the partition might
// contain either the source or the target data, which might be of different lengths. We need to
// know the length in order to read from a partition (there is no "end-of-file" marker), so the
// caller must specify the possible lengths and the hash of the data, and we'll do the load
// expecting to find one of those hashes.
static int LoadPartitionContents(const std::string& filename, FileContents* file) {
std::vector<std::string> pieces = android::base::Split(filename, ":");
if (pieces.size() < 4 || pieces.size() % 2 != 0 || pieces[0] != "EMMC") {
@ -184,8 +178,6 @@ static int LoadPartitionContents(const std::string& filename, FileContents* file
return 0;
}
// Save the contents of the given FileContents object under the given
// filename. Return 0 on success.
int SaveFileContents(const char* filename, const FileContents* file) {
unique_fd fd(ota_open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_SYNC, S_IRUSR | S_IWUSR));
if (fd == -1) {
@ -211,11 +203,10 @@ int SaveFileContents(const char* filename, const FileContents* file) {
return 0;
}
// Write a memory buffer to 'target' partition, a string of the form
// "EMMC:<partition_device>[:...]". The target name
// might contain multiple colons, but WriteToPartition() only uses the first
// two and ignores the rest. Return 0 on success.
int WriteToPartition(const unsigned char* data, size_t len, const std::string& target) {
// Writes a memory buffer to 'target' partition, a string of the form
// "EMMC:<partition_device>[:...]". The target name might contain multiple colons, but
// WriteToPartition() only uses the first two and ignores the rest. Returns 0 on success.
static int WriteToPartition(const unsigned char* data, size_t len, const std::string& target) {
std::vector<std::string> pieces = android::base::Split(target, ":");
if (pieces.size() < 2 || pieces[0] != "EMMC") {
printf("WriteToPartition called with bad target (%s)\n", target.c_str());
@ -343,42 +334,37 @@ int WriteToPartition(const unsigned char* data, size_t len, const std::string& t
return 0;
}
// Take a string 'str' of 40 hex digits and parse it into the 20
// byte array 'digest'. 'str' may contain only the digest or be of
// the form "<digest>:<anything>". Return 0 on success, -1 on any
// error.
int ParseSha1(const char* str, uint8_t* digest) {
const char* ps = str;
uint8_t* pd = digest;
for (int i = 0; i < SHA_DIGEST_LENGTH * 2; ++i, ++ps) {
int digit;
if (*ps >= '0' && *ps <= '9') {
digit = *ps - '0';
} else if (*ps >= 'a' && *ps <= 'f') {
digit = *ps - 'a' + 10;
} else if (*ps >= 'A' && *ps <= 'F') {
digit = *ps - 'A' + 10;
} else {
return -1;
}
if (i % 2 == 0) {
*pd = digit << 4;
} else {
*pd |= digit;
++pd;
}
const char* ps = str;
uint8_t* pd = digest;
for (int i = 0; i < SHA_DIGEST_LENGTH * 2; ++i, ++ps) {
int digit;
if (*ps >= '0' && *ps <= '9') {
digit = *ps - '0';
} else if (*ps >= 'a' && *ps <= 'f') {
digit = *ps - 'a' + 10;
} else if (*ps >= 'A' && *ps <= 'F') {
digit = *ps - 'A' + 10;
} else {
return -1;
}
if (*ps != '\0') return -1;
return 0;
if (i % 2 == 0) {
*pd = digit << 4;
} else {
*pd |= digit;
++pd;
}
}
if (*ps != '\0') return -1;
return 0;
}
// Search an array of sha1 strings for one matching the given sha1.
// Return the index of the match on success, or -1 if no match is
// found.
static int FindMatchingPatch(uint8_t* sha1, const std::vector<std::string>& patch_sha1_str) {
for (size_t i = 0; i < patch_sha1_str.size(); ++i) {
// Searches a vector of SHA-1 strings for one matching the given SHA-1. Returns the index of the
// match on success, or -1 if no match is found.
static int FindMatchingPatch(const uint8_t* sha1, const std::vector<std::string>& patch_sha1s) {
for (size_t i = 0; i < patch_sha1s.size(); ++i) {
uint8_t patch_sha1[SHA_DIGEST_LENGTH];
if (ParseSha1(patch_sha1_str[i].c_str(), patch_sha1) == 0 &&
if (ParseSha1(patch_sha1s[i].c_str(), patch_sha1) == 0 &&
memcmp(patch_sha1, sha1, SHA_DIGEST_LENGTH) == 0) {
return i;
}
@ -386,29 +372,24 @@ static int FindMatchingPatch(uint8_t* sha1, const std::vector<std::string>& patc
return -1;
}
// Returns 0 if the contents of the file (argv[2]) or the cached file
// match any of the sha1's on the command line (argv[3:]). Returns
// nonzero otherwise.
int applypatch_check(const char* filename, const std::vector<std::string>& patch_sha1_str) {
int applypatch_check(const char* filename, const std::vector<std::string>& patch_sha1s) {
// It's okay to specify no SHA-1s; the check will pass if the LoadFileContents is successful.
// (Useful for reading partitions, where the filename encodes the SHA-1s; no need to check them
// twice.)
FileContents file;
// It's okay to specify no sha1s; the check will pass if the
// LoadFileContents is successful. (Useful for reading
// partitions, where the filename encodes the sha1s; no need to
// check them twice.)
if (LoadFileContents(filename, &file) != 0 ||
(!patch_sha1_str.empty() && FindMatchingPatch(file.sha1, patch_sha1_str) < 0)) {
(!patch_sha1s.empty() && FindMatchingPatch(file.sha1, patch_sha1s) < 0)) {
printf("file \"%s\" doesn't have any of expected sha1 sums; checking cache\n", filename);
// If the source file is missing or corrupted, it might be because we were killed in the middle
// of patching it. A copy of it should have been made in cache_temp_source. If that file
// exists and matches the sha1 we're looking for, the check still passes.
// of patching it. A copy should have been made in cache_temp_source. If that file exists and
// matches the SHA-1 we're looking for, the check still passes.
if (LoadFileContents(Paths::Get().cache_temp_source().c_str(), &file) != 0) {
printf("failed to load cache file\n");
return 1;
}
if (FindMatchingPatch(file.sha1, patch_sha1_str) < 0) {
if (FindMatchingPatch(file.sha1, patch_sha1s) < 0) {
printf("cache bits don't match any sha1 for \"%s\"\n", filename);
return 1;
}
@ -417,8 +398,8 @@ int applypatch_check(const char* filename, const std::vector<std::string>& patch
}
int ShowLicenses() {
ShowBSDiffLicense();
return 0;
ShowBSDiffLicense();
return 0;
}
static size_t FileSink(const unsigned char* data, size_t len, int fd) {
@ -434,8 +415,6 @@ static size_t FileSink(const unsigned char* data, size_t len, int fd) {
return done;
}
// Return the amount of free space (in bytes) on the filesystem
// containing filename. filename must exist. Return -1 on error.
size_t FreeSpaceForFile(const std::string& filename) {
struct statfs sf;
if (statfs(filename.c_str(), &sf) != 0) {
@ -446,37 +425,16 @@ size_t FreeSpaceForFile(const std::string& filename) {
}
int CacheSizeCheck(size_t bytes) {
if (MakeFreeSpaceOnCache(bytes) < 0) {
printf("unable to make %zu bytes available on /cache\n", bytes);
return 1;
}
return 0;
if (MakeFreeSpaceOnCache(bytes) < 0) {
printf("unable to make %zu bytes available on /cache\n", bytes);
return 1;
}
return 0;
}
// This function applies binary patches to EMMC target files in a way that is safe (the original
// file is not touched until we have the desired replacement for it) and idempotent (it's okay to
// run this program multiple times).
//
// - If the SHA-1 hash of <target_filename> is <target_sha1_string>, does nothing and exits
// successfully.
//
// - Otherwise, if the SHA-1 hash of <source_filename> is one of the entries in <patch_sha1_str>,
// the corresponding patch from <patch_data> (which must be a VAL_BLOB) is applied to produce a
// new file (the type of patch is automatically detected from the blob data). If that new file
// has SHA-1 hash <target_sha1_str>, moves it to replace <target_filename>, and exits
// successfully. Note that if <source_filename> and <target_filename> are not the same,
// <source_filename> is NOT deleted on success. <target_filename> may be the string "-" to mean
// "the same as <source_filename>".
//
// - Otherwise, or if any error is encountered, exits with non-zero status.
//
// <source_filename> must refer to an EMMC partition to read the source data. See the comments for
// the LoadPartitionContents() function above for the format of such a filename. <target_size> has
// become obsolete since we have dropped the support for patching non-EMMC targets (EMMC targets
// have the size embedded in the filename).
int applypatch(const char* source_filename, const char* target_filename,
const char* target_sha1_str, size_t /* target_size */,
const std::vector<std::string>& patch_sha1_str,
const std::vector<std::string>& patch_sha1s,
const std::vector<std::unique_ptr<Value>>& patch_data, const Value* bonus_data) {
printf("patch %s: ", source_filename);
@ -515,7 +473,7 @@ int applypatch(const char* source_filename, const char* target_filename,
}
if (!source_file.data.empty()) {
int to_use = FindMatchingPatch(source_file.sha1, patch_sha1_str);
int to_use = FindMatchingPatch(source_file.sha1, patch_sha1s);
if (to_use != -1) {
return GenerateTarget(source_file, patch_data[to_use], target_filename, target_sha1,
bonus_data);
@ -530,7 +488,7 @@ int applypatch(const char* source_filename, const char* target_filename,
return 1;
}
int to_use = FindMatchingPatch(copy_file.sha1, patch_sha1_str);
int to_use = FindMatchingPatch(copy_file.sha1, patch_sha1s);
if (to_use == -1) {
printf("copy file doesn't match source SHA-1s either\n");
return 1;
@ -539,13 +497,6 @@ int applypatch(const char* source_filename, const char* target_filename,
return GenerateTarget(copy_file, patch_data[to_use], target_filename, target_sha1, bonus_data);
}
/*
* This function flashes a given image to the target partition. It verifies
* the target cheksum first, and will return if target has the desired hash.
* It checks the checksum of the given source image before flashing, and
* verifies the target partition afterwards. The function is idempotent.
* Returns zero on success.
*/
int applypatch_flash(const char* source_filename, const char* target_filename,
const char* target_sha1_str, size_t target_size) {
printf("flash %s: ", target_filename);

58
applypatch/include/applypatch/applypatch.h
View file

@ -39,23 +39,61 @@ using SinkFn = std::function<size_t(const unsigned char*, size_t)>;
// applypatch.cpp
int ShowLicenses();
// Returns the amount of free space (in bytes) on the filesystem containing filename, or -1 on
// error. filename must exist.
size_t FreeSpaceForFile(const std::string& filename);
// Checks whether /cache partition has at least 'bytes'-byte free space. Returns 0 on having
// sufficient space.
int CacheSizeCheck(size_t bytes);
// Parses a given string of 40 hex digits into 20-byte array 'digest'. 'str' may contain only the
// digest or be of the form "<digest>:<anything>". Returns 0 on success, or -1 on any error.
int ParseSha1(const char* str, uint8_t* digest);
int applypatch(const char* source_filename,
const char* target_filename,
const char* target_sha1_str,
size_t target_size,
const std::vector<std::string>& patch_sha1_str,
const std::vector<std::unique_ptr<Value>>& patch_data,
const Value* bonus_data);
int applypatch_check(const char* filename,
const std::vector<std::string>& patch_sha1_str);
// Applies binary patches to eMMC target files in a way that is safe (the original file is not
// touched until we have the desired replacement for it) and idempotent (it's okay to run this
// program multiple times).
//
// - If the SHA-1 hash of 'target_filename' is 'target_sha1_string', does nothing and returns
// successfully.
//
// - Otherwise, if the SHA-1 hash of 'source_filename' is one of the entries in 'patch_sha1s', the
// corresponding patch from 'patch_data' (which must be a VAL_BLOB) is applied to produce a new
// file (the type of patch is automatically detected from the blob data). If that new file has
// SHA-1 hash 'target_sha1_str', moves it to replace 'target_filename', and exits successfully.
// Note that if 'source_filename' and 'target_filename' are not the same, 'source_filename' is
// NOT deleted on success. 'target_filename' may be the string "-" to mean
// "the same as 'source_filename'".
//
// - Otherwise, or if any error is encountered, exits with non-zero status.
//
// 'source_filename' must refer to an eMMC partition to read the source data. See the comments for
// the LoadPartitionContents() function for the format of such a filename. 'target_size' has become
// obsolete since we have dropped the support for patching non-eMMC targets (eMMC targets have the
// size embedded in the filename).
int applypatch(const char* source_filename, const char* target_filename,
const char* target_sha1_str, size_t target_size,
const std::vector<std::string>& patch_sha1s,
const std::vector<std::unique_ptr<Value>>& patch_data, const Value* bonus_data);
// Returns 0 if the contents of the file or the cached file match any of the given SHA-1's. Returns
// nonzero otherwise.
int applypatch_check(const char* filename, const std::vector<std::string>& patch_sha1s);
// Flashes a given image to the target partition. It verifies the target cheksum first, and will
// return if target already has the desired hash. Otherwise it checks the checksum of the given
// source image before flashing, and verifies the target partition afterwards. The function is
// idempotent. Returns zero on success.
int applypatch_flash(const char* source_filename, const char* target_filename,
const char* target_sha1_str, size_t target_size);
// Reads a file into memory; stores the file contents and associated metadata in *file. Returns 0
// on success, or -1 on error.
int LoadFileContents(const char* filename, FileContents* file);
// Saves the given FileContents object to the given filename. Returns 0 on success, or -1 on error.
int SaveFileContents(const char* filename, const FileContents* file);
// bspatch.cpp
@ -79,9 +117,9 @@ int ApplyImagePatch(const unsigned char* old_data, size_t old_size, const Value&
// freecache.cpp
int MakeFreeSpaceOnCache(size_t bytes_needed);
// Removes the files in |dirname| until we have at least |bytes_needed| bytes of free space on
// the partition. The size of the free space is returned by calling |space_checker|.
bool RemoveFilesInDirectory(size_t bytes_needed, const std::string& dirname,
const std::function<size_t(const std::string&)>& space_checker);
#endif